1. Field of the Invention:
This invention relates to a guide tube for guiding a slider drive member in a passive seat belt system of the type that an occupant-restraining webbing is automatically brought into contact with or brought away from the body of an occupant.
2. Description of the Related Art
FIGS. 12 and 13 illustrate one example of passive seat belt systems known to date inter alia from from Japanese Utility Model Application Laid-Open Nos. 76555/1985, 61262/1986 and 8856/1987. A residual portion of an occupant-restraining webbing 1 is wound into an inner retractor 3 provided on a lower part of the inboard side wall of a seat 2, while the free end of the webbing 1 is fastened to a slider 5 by way of an emergency release buckle 4. The slider 5 is received within a slide rail 7 mounted on a roofside portion of the inner wall of a roof of a vehicle body 6 in such a way that the slider 5 is movable along the length of the vehicle body. The slider 5 is driven by an unillustrated drive member, such as a drive wire or drive tape, which is paid out and taken up by a drive unit 8. The drive unit 8 is actuated responsive to each opening or closure of an associated door. Although not seen in the drawings, there is a reel inside the drive unit 8. The reel is connected to a motor which is not seen either in the drawings. The drive member is wound on the reel so that the drive member may be selectively paid out or taken up. An anchor latch 9 is provided at the rear end of the slide rail 7. Arranged between the anchor latch 9 and the drive unit 8 is a guide tube 10 made of a synthetic resin and adapted to guide the movement of the guide drive member.
Numeral 13 indicates rail brackets for mounting the slide rail 7 on the vehicle body 6.
By the way, the material and shape of the guide tube 10 are chosen to give low flexural rigidity so that the guide tube 10 may be bent three-dimensionally to conform in configuration with the inner wall of the vehicle body 6. Upon driving the slider 5, especially upon hindrance of smooth movement of slider 5 for some reasons, the drive member is prone to wavy deformation relative to the length thereof by the pushing force applied thereto. Once such a deformation takes place, the surface of the drive member is brought under pressure into contact the inner wall of the guide tube 10. There is thus the potential danger that the guide tube 10 itself may be bent into a wavy shape and the smooth movement of the drive member within the guide tube 10 may hence be impaired due to friction therebetween. To avoid such inconvenience, it has been the conventional practice to fix the guide tube 10 over substantially the entire length thereof on the vehicle body 6 by using many tube brackets 11 made of a metal, thereby preventing bending of the guide tube 10 itself.
When the guide tube 10 is arranged along the vehicle body, it has been the conventional practice to form the tube 10 with a synthetic resin material by extrusion, to insert the tube 10 through the tube brackets 11 and then to fix the tube brackets on the vehicle body by using bolts and nuts welded on the side of the vehicle body.
In addition, the slide rail 7 employed in the passive seat belt system is provided with limit switches 12, 12 for detecting movements of the slider 5 to predetermined front and rear positions of the vehicle body, respectively. Further, the emergency release buckle 4 is provided with a warning switch for detecting whether a tongue fastened to the free end of the webbing 1 is latched in the buckle 4. It is thus necessary to feed a current to these limit switches 12 and warning switch through wire harnesses 14. It has been the conventional practice to attach these wire harnesses 14 to the vehicle body subsequent to the mounting of the slide 7 on the vehicle body and then to connect them to the limit switches 12, 12 and warning switch respectively.
The above conventional practice has however led to the need for many tube brackets 11, many points on the vehicle body 6 for the attachment of the tube brackets 11 and many attachment steps for the tube brackets 11, thereby making it difficult to reduce the cost for the assembly and manufacture of a passive seat belt system.
It has also been necessary to fit the tube brackets 11 over the tube 10 and then to precisely position the tube brackets 11 relative to the tube 10. Here, fitting errors tend to occur. Further, the positions of the tube brackets 11 fixed on the tube 10 are usually out of registration with the positions of the nuts welded on the vehicle body so that the positions of the tube brackets 11 have to be adjusted before their attachment to the vehicle body.
It was contemplated of temporarily holding the tube brackets 11 on the tube 10 with an adhesive plastic tape or the like to position the former precisely on the latter. This method however required complex attachment steps, because the handling of the tape was inconvenient and the positions of the tube brackets 11 were susceptible to displacement.
In the above-described prior art, in addition to the guide tube 10, the wire harnesses 14 were also fixed at plural locations on a center pillar or the like of the vehicle body 6 by plural clips or similar means or on the guide tube 10 for the drive member by using an adhesive plastic tape or the like. This led to an increased assembly step number and increased part number and made it difficult to attach the wire harnesses 14 because of the cumbersome handling of the adhesive plastic tape. As a consequence, it was difficult to reduce the assembling and manufacturing cost.